System and apparatus employing the &#34;hall effect&#34;



Oct. 6, 1931. P. H, CRAIG 1,825,855v

SYSTEM AND APPARATUS EMPLOYING THE"HALL EFFECT" Original Filed July 9,1926 2 Sheets-Sheet 2 /A/par 27 6?/ SMU/(tr or A513025 IN V EN TOR.

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Patented Oct. 6, 1931 UNITED STATES PALMER. HUNT CRAIG, OF CINCINNATI,OHIO, ASSIGNOR TO INVEX CORPORATION, .A

PATENT omer.

CORPORATION OF NEW YORK SYSTEM AND .APPARATUS EMPLOYING THE HALL EFFECTOriginal application filed July 9, 1926, Serial No. 181,894. Divided andthis application led January 14, 1929. Serial No. 832,545.

' metallic plates when subjected to the action of a longitudinal currentand the influence of a magnetic field.

This application is a division of my applio cat-ion S. N. 121,394, filedJuly 9, 1926 for system and apparatus employing the Hall effect.

One of the objects of my invention is to provide a. device consisting ofa plurality of rectangular metallic foil sheets or metallic alloy platesin stacked arrangement insulatcd one from another and electricallyconnected in parallel at opposite ends thereof and in series along thetransverse axis thereof, whereby current of direct currentcharacteristic may be secured in a circuit which connects to pointsalong the transverse axes of the plates when alternating current issupplied to the opposite end of1 the plates and a magnetic field createdaround the plates.

Another object of my invention is to provide a construction of fixedrectifier for alf ternating current which remains in permanentadjustment and does not require resetting from time to time.

Another object of my invention is to provide a device for modifyingelectrical currcnt of alternating characteristic for rectifying,amplifying or causingthe generation of electrical oscillations of anyselected frequency.

Still another object of my invention is to provide. an electricalapparatus particularly adapted for operation in conjunction with thecircuits of a radio receiving system foi rendering feeble signalcurrents observable.

A still further object of my invention is to provide an apparatus unitwhich may be connected in circuit. with electron tube apparatus forfacilitating the operation of the electron tube apparatus in thereception of signaling energy.

Other and further objects ofmy invention will be understood from thespecification hereinafter following by reference to the accompanyingdrawings in which:

Figure 1 represents in perspective View the arrangement of parts in theapparatus of my invention; Fig. 2 is an end View of the apparatusshowing more clearly the direction of the magnetic field perpendicularto the plane of the metallic plates; Fig. 3 is a schematic view showingthe arrangement of the metallic films which comprise the apparatus of myinvention; Fig. 4 is a diagrammatic view showing the wiring arrangementof the apparatus of my invention when used as a recti fier; Fig. 5 showsone Iof the a plications of my invention in a refiex signaling receivingcircuit; Fig. 6 illustrates an application of my invention as a detectorin aradio receiving circuit; Fig. 7 shows a circuit arrangement whichmakes use of the principles of my ine vention in the amplification ofsignal energy, provision being made for facilitating the produc-tion ofoscillations; Fig. 8 shows a circuit arrangement wherein thelongitudinal cur- 'rent which passes through the plates of the apparatusof my invention is derived from a source independent of the source whichcreates the magnetic field 'aboutthe plates; Fig. 9, illustrates acircuit arrangement employing a, plurality of the devices of myinvention as an amplifier of incoming signaling energy and as arectifier of the amplified energy; and Fig. 10 shows the fundamentalarrangement of the magnetic field transverse to the plane of the severalmetallic films in the apparatus for ldeveloping the principles set forthherein.

My invention makes use of the Hall,

sol

Corbino and similar electromagnetic phenomena for the rectification oramplification of alternating currents, and the generation of sustainedelectrical oscillations in electrical circuits.

The Hall effect consists, briefly, of an electromagnetic henomenaobservable when a strip or film o metal carryin a longitudinal currentI, (Fig. 3) is placed 1n a magnetic field perpendicular to the plane ofsuch a strip, a transverse potential difference being set up between theedges a, a', of the strip,

this difference of potential being approximately, under normalconditions, represented by the direct current formula:

Where E=the transverse potential difference;

I=the current (longitudinal) through the strip;

d=the thickness of the strip.

H=the magnetic field strength.

The Corbino effect is similar to the Hall effect, wherein a radialcurrent through a circular disc subjected to a magnetic fieldperpendicular to the plane of the disc, produces a circular currentthrough the disc.

I I have discovered that if plates or films ofmetal such as bismuth,tellurium, bismuth-antimony alloy, or other metal or alloy, be connectedas shown in the drawings, the device will act as a practical rectifierof impressed alternating currents. Referring to the drawings in Fig. 4,the alternating current is sent through the strip Z from c to d, inone-half of the cycle, and from d it enters the solenoid S, being an aircore or a core of magnetic material, thence after passing through thesolenoid it returns to the alternating current source. In the other halfof the cycle the operation is, of course, reversed. t

Fig. 4 also shows the method of stacking many plates 1, 2 and 3 on topof one another, with suitable insulation between, and then connectingthe positive Hall effect potential point of one plate to the negativeHall7 effect potential point of the one below, as represented in thedrawings at e, f, g, It, z' and j. In other words, the transversepotential of all of the plates l, 2 and 3 are put in series in order toadd up to larger values of potential than would be obtained with asingle plate.

It is obvious, that since the polarity of the Hall effect potentialdifference changes in synchronism with either the change in polarity ofthe points c and (Z, or with the change in direction of the magneticfiuX through the plate, the polarity of the points c, y', (Fig. 4) willalways be the same with respect to each other when both the magneticflux and also the longitudinal current through the plates change inphase and synchronously with each other. The arrangement shown in Fig. 4will then obviously give a pulsating direct current at the points e,

The construction of the apparatus of my invention is more clearlyillustrated in Fig. 1 where the metallic films have been represented atl, 2, 3, 4 and 5 separated by insulated sheets 7. Opposite ends of thefilms are tapped as represented at c and d. The transverse axes of thefilms are connected in series as represented at e, f, g, 71., z', j, k,Z, m

and fn, for delivering a direct current. The end view of the apparatusin Fig. 2 shows more clearl the arrangement of the films and theielectric sheets. The solenoid winding has been divided into twosections for producing a transverse magnetic field through the metallicfilms.

In Fig. 3 I have shown a stacked arrangelnent of metallic filmsseparated by insulated sheetsin accordance with my invention, where thealternating current I passes along the longitudinal axes of the filmsfrom d to c. I provide copper end contacts 8 and 9 which bridge all ofthe metallic films enabling the films to be connected in the electricalcircuit in parallel. The point contacts across the transverse axes ofthe films have been represented at a and a.

The device may be used as a rectifier in ordinary electrical circuitswhere the power drawn from the rectifier is of sufficiently low value soas to render the method practicable. The arrangement can also be used asa rectifier in radio transmitters and receivers, especially to replacethe crystal detector or the triode vacuum tube detector in radioreception. It could be used either alone or in combination with electrontubes, a typical circuit diagram of the latter method being given inFig. 5.

Referring to the drawings in more detail the receiving antenna system isrepresented at 10 which connects to a ground system at 11 with acoupling inductance 12 therein coupled to the tuned input circuit 14 ofthe electron tube 15 which functions asa radio frcquency amplifier. Theoutput of the radio frequency amplification circuit 15 connects througha tuned circuit 16 with the input circuit of a second stage of radiofrequency amplification constituted by electron tube 18, the outputcircuit of which includes transformer system 17 tuned as represented at2S for supplying exciting current to the solenoid S through a seriescircuit which passes through the longitudinal axes of the metallic filmsfrom points d to C. A direct current is derived across the points ofcontact a and a which is directly proportional to the incoming signalingenergy. The rectified current is l delivered through a transformersystem 20 to the input circuit of the electron tube 18 which alsofunctions as an audio frequency amplification system delivering itsaudio frequency output through transformer 19 with the input circuit ofelectron tube 15 which serves also to amplify at audio frequencydelivering its output to telephones T. Battery A supplies filamentheating current for the several tubes while battery B supplies spacecurrent for the tubes. The tuned system 17-28 permits a relatively largevalue of current to pass through the metallic films and thereby securesmaximum direct current energy across the transverse axes of the metallicfilms. My nventionl may be applied to all standard circuits as well asto the reflex system of Fig. 5.

Referring to Fig. 6 a simplified circuit is illustrated showing theapplication of the principle of my invention to a simple radioreceivingapparatus. In this circuit the incoming signaling energy delivered fromtuned circuit 14 passes through the longitudinal axes of the metallicfilms from d to c at the same time setting up a magnetic field by meansof solenoid S for deriving direct current across the transverse axesofthe metallic films at a and a proportionate to the incoming signalingenergy. This direct current directly actuates the telephone responsivedevice T.

It should be noted that, due to the fact that this system is a perfectrectifier (that is, it admits of no inverse potential or currents in theoutput) it Wil-l produce no distortion in the reproduction of radiotelephone signals and voice, and is, therefore, far superior to eitherthe crystal detector or the electron tube from the standpoint offaithful reproduction, in addition to its superior qualities ofstability, ease of operation and lower cost of maintenance.

Fig. 7 illustrates a circuit arrangement which I employ in theamplification of signaling energy by means of the apparatus of myinvention. An input circuit has been illust-rated in the form of aninductive coupler 25 tuned by variable condenser 26 and connectedthroughv the longitudinal axes of the metallic films at cl and c. Apermanent magnetic field may be'established about the meta-llic films bymeans of a local source 21 connected in circuit with the winding S. Aniron core may be provided for this solenoid S. Incoming signaling energyis supplied through winding 27 coupled with the windings 25. Thetransverse axes of the films at a and a are connected in series with alocal source 22 and an inductance 24 which couples with the inductancesystem 25. A desired degree of regenerative amplification is thusintroduced for increasing the amplitude of the impulses of signalingenergy delivered to the out-put circuit. The principle of my inventionmay be applied to an oscillator where the input coil 27 connects to asmall local exciter of alternating current and the output connectedthrough a transformer system. By employing selected values ofinductance, capacity and resistance the systcm may be arranged tooscillate at either audio or radio frequencies.

Fig. 8 illustrates a method of obtaining greater energy amplification inthe apparatus of my invention. A permanent magnetic flux is set upthrough the thickness of the plates and also a permanent longitudinalcurrent is established along the horizontal axes of the plates from abattery 28. A tuned input circuit system 27-25-26 is arranged to excitethe winding S which encloses the stack of alternately positioned filmsand dielectric sheets. The longitudinal axes of the films are connectedat points a and a with an output circuit including a source of potential22' and indu'ctance 24. The inductance 24 is induetively coupled to aninductance 29 tuned by means of condenser 30 in the output circuit ofthe electrical s stem. The iiuctuating magnetic field from t e winding Swhich va- `ries in proportion to the amplitude of the signaling energyis superimposed on the permanent field which is established.

The input may also be superim osed on the longitudlnal current instead oupon the magnetic field. The local battery for supplying longitudinalcurrent tothe conductive films may thus be eliminated. The local batteryin the circuit of the electrical system is provided to boost the voltageof the output f to the proper value for the operation of succeedingamplifier stages or the reproducing unit, the Hall fluctuating potentialbeing then superimposed upon this steady potential. By increasing thenumber of conductive films in parallel the eective potential may also beincreased.

In Fig. 9 I have shown an application 4of my invention to an electrontube circuit where the conductive films have their longitudinal axesconnected in series in the output circuit of electron tube l5. Aconstant magnetic field is supplied from battery 2l to the winding S. Inthis manner the device operates as a radio frequency amplifier,delivering amplified energy to an output circuit across the transverseaxes of the conductive films in series as represented at e and j, theoutput circuit including battery 22 and solenoidal Winding S. Thesolenoidal winding S connects in series with the longitudinal axes ofconductive films as represented at c and d and across the transverseaxesat a and a I connect the output circuit which includes the battery22. The arrangement of the conductive films within the solenoidalWinding S serves as a rectifier of amplified energy delivered by theconductive films within the solenoidal winding S.

Fig. 10 shows a method I may employ for setting up the magnetic fieldwhich threads through the conductive films. A pair of compressed siliconsteel filing cores-or other suitable magnetic material or alloysarearranged on opposite sides of the stack of alternately positionedconductive films and dielectric sheets. On these coils are provided thewindings S2 and S3 supplied from the local source 2l. The stack ofbismuth or metallic alloy conductive films may be quite thick but themagnetic field is concentrically normal to the plane of the conductivefilms. Permanent magnets may also be employed instead of electromagnets.

' It will be understood that I may employ conductive films of alloys,metals, crystals or chemical salts in lieu of the bismuth filmsmentioned herein. Photo-electric materials may be provided for thefilms. In some 1nstances, I may produce the bismuth films by cathodicsputtering, thus making the films very thin. The transverse currenteffect 1s inversely proportional to the thickness of the film and whenthe films, which are often so thin as to be transparent to light, aredeposited on thin mica approximately 100 films are connected in seriestransversely for securing desired operation. The magnetic field in somecases is produced by a solenoidal coil of approximately 1,000 turns oncores of compressed silicon steel filings. The resultant transversepulsating direct current 1s several volts for only one milliampereflowing through the field coil and longitudinally through the conductivefilms in parallel. I have found that Where four amperes alternatingcurrent at 60 cycle frequency is passed through a l2 turn coil and thenthrough the conductive films connected in parallel with themselveslongitudinally, the resulting pulsating direct current component acrosseach conductive filmis approximately 50 microvolts. When the conductivefilms in the number above referred to are connected in seriestransversely 200 micro-volts may be obtained. The values obtainable mayreadily be used in the operation of electron tubes. The arrangement ofthe apparatus is such that connections may be readily made with electrontube circuits directly in the input circuit of an electron tube asrepresented at Fig. 9 without the interposition of transformer systems.

'When an iron core is used with the device of my invention with theproper permeability curve an asymmetric characteristic curve may beobtained with the device similar to that obtained with a triode tube.This ability of the device of my invention facilitates the generation ofself-oscillations in the device. The device when properly connectedwill,therefore, operate as an amplifier or as an oscillator in addition toits properties as a rectifier. `While I have described my invention incertain preferred embodiment-s, I desire that it be understood thatvarious modifications may be made without departing from the spirit ofthe appended claims.

lVhat I claim as new and desire to secure by Letters Patent of theUnited States is as follows:

1. In a radio system, a radio frequency energy collecting circuit, aresponsive system and means interposed between said radio frequencyenergy collecting circuit and said responsive system comprising a stackof alternately positioned conductive and dielectric films, each of saidconductive films having longitudinal and transverse axes, a windingenclosing said films for establishing a magnetic field normal to thesurface thereof, said Winding being connected in series with thelongitudinal axes of said films in' parallel, a circuit connectionbetween said radio frequency energy collecting circuit and said winding,and a circuit connection between the transverse axes of said conductivefilms and said responsive system whereby incoming signaling energy maybe rectified and observed.

2. A radio receiving system comprising a radio frequency energycollecting circuit, a responsive system and means interposed betweensaid radio frequency energy collecting circuit and said responsivesystem comprising a plurality of alternately positioned conductive filmsand dielectric sheets, each of said conductive films having longitudinaland transverse axes, parallel connections between the edges of saidconductive films along the longitudinal axes thereof andseriesconnections between the opposite edges of said conductive filmsalong the transverse axes thereof and a winding connected with saidradio frequency energy collecting circuit and surrounding saidconductive films for creating a fiuctuating magnetic field variable inproportion to the amplitude of the incoming signaling en'ergy in adirection normal to the plane of said conductive films whereby a directcurrent is established along the transverse axes of said conductivefilms and connections between the transverse axes and said responsivesystem for controlling said responsive system in accordance withincoming signaling energy.

3. In a signal receiving system a high frequency signal receivingcircuit, a plurality of alternately positioned conductive and dielectricfilms, said conductive films having their longitudinal axes connected inparallel at the edges of said films, each of said conductive filmshaving a connection along the transverse axis thereof from the edge ofone conductive film to the opposite edge of an adjacent conductive film,a signal responsive circuit connected across the transverse axes of saidconductive films and a winding for establishing a magnetic fieldsubstantially normal to the plane of said conductive films, said windingbeing connected with said high frequency signal receiving circuit forvarying said magnetic field synchronously with the variations of theincoming signaling energy, whereby the incoming signahng energy isrectified and caused to operate said signal responsive circuit.

4. A signal receiving system comprising a tuned input circuit responsiveto modulated signaling energy, a multiplicity of conductive sheets eachpossessing Hall effect positioned parallel one with respect to the otherand separated by dielectric sheets,connections between said tuned inputcircuit and the longitudinal axes of said conductive sheets forenergizing the conductive sheets along the films connected in series andmeans for indilongitudinal axes thereof, means for creating eating thecurrent in the circuit through the a variable magnetic field normaltosaid sheets, transverse axes of said conductive films.

said means being connected with said timed circuit and operatedaccording to the changes in amplitude of the received signaling energyand a signal observing circuit connected across the transverse axes ofsaid sheets and operative by the efl'ects of the variable magnetic fieldupon said sheets.

5. In a signal receiving system a. tuned input circuit, a multiplicityof alternately positioned conductive and dielectric sheets superimposedone with respect to another, said conductive sheets each possessing Halleffect, an inductance surrounding said sheets and electrically connectedwith said tuned input circuit for establishing a magnetic field noi'-mal to said sheets variable synchronousl with the modulation of theincomingsigna ing energy impressed upon said tuned input circuit, aconnection between said tuned input circuit and the longitudinal axes ofsaid conductive sheets in parallel for energizing said sheets alon thelongitudinal axes thereof, and a circuit connected with the transverseaxes of said conductive sheets in parallel for responding to the effectsof the variable magnetic field upon said conductive sheets. l

6. In a signal receiving system a tuned input circuit, a multiplicity ofalternately positioned conductive and dielectric sheets positioned inplanes parallel one to the other, said conductive sheets each possessingHall effect, a winding adjacent said sheets for establishing a magneticfield penetrating said sheets substantially normal to the surfacethereof, a series circuit interconnecting the longitudinal axes of saidconductive sheets, said tuned in ut circuit and said windin whereby mulated signaling eriergy is impressed uplon said winding for varying themagnetic eld through said sheets, and an independent circuit connectedto the transverse axes of said conductive sheets in series fortransferring the effects of said variable magnetic field to a signaltranslating circuit.

7. A signal receiving system comprising a high frequency energycollectin circuit, an oscillatory circuit connected wit said highfrequency energy collecting circuit, a multiplicity of alternatelypositioned conductive and dielectric films superimposed one with respectto another, a winding surrounding said superimposed films forestablishing a magnetic field substantially normal to the surface of theconductive films, circuit means for causing incoming oscillations imressed upon said radio frequency energy co lectin v circuit to passlongitudinally through sai conductive films in parallel and through saidwindin whereby a unidirectional current is establis ed transversely ofsaid conductive In testimony whereof I affix my signature.

ALMER HUNT CRAIG.

